1. Field of the Invention
The invention relates to an image forming apparatus for forming a sample image onto a recording medium and for controlling image forming conditions on the basis of a state of the sample image.
2. Related Background Art
In recent years, in U.S. Pat. No. 4,888,636, U.S. Ser. No. 760505, now U.S. Pat. No. 5,406,390, and the like, there have been proposed several control methods whereby in order to stabilize an image density which is generated in a full-color copying apparatus, a specific pattern is formed on an image carrier and an optical density of the pattern is read and fed back to a toner supplemental amount and image forming conditions.
In the case of actually applying such image stabilizing controls, there is a method of manually actuating such a control by the user or service person or a method of automatically actuating such a control. It is considered that the automatic actuating method is preferable when considering from the side of the user of the apparatus.
In the foregoing U.S. Pat. No. 4,888,636, since the feedback control is actuated by the service person, there is a drawback such that in the case where an image deterioration occurs, a proper image cannot be obtained until the service person comes.
According to the foregoing U.S. Ser. No. 760505, when a power switch is turned on or after the elapse of a predetermined time from the turn-on of the power switch, the feedback control is automatically executed.
However, when the feedback control (image stabilizing control) is actuated at the time of turn-off/on of the power source of the image forming apparatus, feedback control is also actuated even at the time of a recovery of a simple error which is recovered by the on/off operation of the power source, so that it takes a time to recover the machine. There is a possibility such that the copying operation of the user is remarkably obstructed.
Since the image stabilizing control operation requires a long time, therefore, in the case of automatically actuating such a control, it is an important point at which stage of the machine which is used the control is actuated in order to improve the convenience for the user.